A survey of teachers has suggested that girls' behaviour in the classroom is worse now than five years ago.
According to a poll by the Association of Teachers and Lecturers, a fifth believe girls are now more difficult than boys.
Almost half thought the behaviour of girls had deteriorated over the past five years, with nearly as many saying it had got worse in the past two years.
The poll of more than 800 teachers found boys were more likely to be disrespectful and verbally and physically aggressive and girls were more likely to be bullies.
Four times as many teachers had seen girls bullying than boys, making snide comments or leaving a fellow pupil out.
"Girls are often sneakier. They often say nasty things which end up disrupting the lesson just as much as the boys," the Daily Express quoted one primary teacher as saying.